Sunday poll is not a forecast: What the Deutschlandtrend can measure
Field period, sample size, margin of error: why a voting-intention survey does not pre-empt an election result – and which details are missing for the September 2026 edition.
Anyone reading the ARD-Deutschlandtrend sees percentages first. They only become readable with four details: the field period, the number of respondents, the survey method and the statistical margin of error. If even one of these figures is missing, it is impossible to judge how robust a gap between two parties really is. How large the margin of error turns out depends on the sample size and the survey design – without these details it remains undetermined.
A snapshot of sentiment with an expiry date
According to the commissioning broadcasters, the ARD-Deutschlandtrend is conducted regularly on behalf of ARD; the body responsible and the frequency are not confirmed from primary sources in this research. Regardless, the same mechanics apply to every Sunday poll: respondents are asked about their voting intention at the moment of the survey. The result describes a party preference within a specific time window, not the outcome of a later vote.
Much shifts between the survey and the election. Undecided voters make up their minds, some vote tactically, and short-term events during the campaign change the starting position. A snapshot therefore does not become a forecast. The term 'Sonntagsfrage' – the Sunday question – means exactly that: the answer to the question of whom one would vote for if the election were held next Sunday – not who will win on election day.
What is missing for the September edition
For the September 2026 edition, none of these details are available in this research. The edition page from Infratest dimap, the press release in the WDR press portal and the topic page from tagesschau.de could not be retrieved and therefore could not be checked. The component '20260903' visible in the WDR path is a file name and proves neither the survey date nor the publication date; the path also contains an obvious typo with 'poitische_stimmung', which must be corrected before any linking.
The tagesschau address leads to a topic page that is continually overwritten, not to a dated single edition. That also leaves open whether the broadcaster's communication and the institute cite the same figures. A comparison of sources would be instructive precisely because broadcaster texts and institute reports can differ in detail: with field period, sample size and margin of error on one side, with bare headline figures on the other.
The only tangible date
Only a legal framework is tangible at present. Under Article 39(1) of the Basic Law, the Bundestag election takes place no earlier than 46 and no later than 48 months after the start of the electoral term. If the 21st Bundestag convened on 25 March 2025 – this date too is not officially confirmed here – the window would run from the end of January to the end of March 2029. This derivation rests solely on the constitutional provision and must be checked against an official source before use. It also says only when an election must be held, not how.
Studies exist on how accurately voting-intention surveys hit their mark. The report by the British Polling Council and the NCRM on the British polls before the 2015 general election (Sturgis report, 2016) and the AAPOR's analysis of the 2016 US presidential election polls (2017) are regarded as references. Neither was retrieved in this research and both may serve as evidence only after verification. They do, however, indicate the direction of the open question: deviations between polls and results have repeatedly been examined systematically.
For publication, that means: first the original pages must be retrieved, the publication date and field period secured, the sample size and method documented, and the party figures compared. Only then can it be assessed what the September 2026 edition shows. A Swiss angle does not follow automatically: Switzerland is neither an EU member nor entitled to vote in German Bundestag elections. Whether trade or migration policy dossiers offer a connecting point would have to be demonstrated separately – it must not be assumed.
Sources
- Infratest dimap – ARD-Deutschlandtrend, September 2026 edition page (address as entered by the editorial team) (Secondary source)
- WDR Presseportal – press release on the Deutschlandtrend (address as entered by the editorial team, with a typo in the path) (Secondary source)
- tagesschau.de – Deutschlandtrend topic page (Secondary source)
- Basic Law for the Federal Republic of Germany, Art. 39 (electoral term, election date) (Secondary source)
